Incorporating passenger molecules, such as pharmaceutical active ingredients, in lipid vesicles, such as liposomes, has been reported in the prior art. An amphipathic carrier structure denoted as a Solvent Dilution Microcarrier (“SDMC”) was disclosed in U.S. Pat. No. 5,269,979. In general, the '979 patent described making a plurality of SDMC vehicles by solubilizing an amphipathic material and a passenger molecule in a first quantity of a non-aqueous solvent. Following this, a first quantity of water was added, forming a turbid suspension. In a subsequent step, a second quantity of non-aqueous solvent was added to form an optically clear solution. The final step of a preferred embodiment was to organize the optically clear solution into SDMC vehicles by mixing with air or a second quantity of water.
In U.S. Pat. No. 5,879,703, a method for preparing a shelf-stable precursor solution useful for remote encapsulation of active ingredients was described. In '703, the precursor solution was made by solubilizing an amphipathic material in a non-aqueous solvent. A quantity of water was added to the first mixture to form a precursor solution characterized by optical clarity and being monophasic at room temperature. The precursor solution could be stored for an extended period of time—and the desired active ingredient added at a later time, perhaps at a remote location, to form a loaded precursor solution. SDMCs could be formed, in preferred embodiments, from the loaded precursor solution by diluting with water or mixing with air. SDMCs ranged from about 230 to about 412 nanometers in size.
Although SDMCs and the shelf-stable precursor solution provided for making vehicles suitable for delivering active ingredients in a variety of applications, a need remained for improved vehicles for delivery of passenger molecules.
It has now been found that the shelf-stable precursor solution such as described in the '703 patent can be used as a starting material in a novel method which results in vehicles of a smaller size than previously reported. The starting material is manipulated by dilution with a non-aqueous solvent, either before or after loading with a passenger molecule, to provide one or more defined populations of nanolipidic particles (“NLPs”) which range in size from about 1 nanometer to about 20 nanometers. NLP assemblies are formed from the NLPs which range in size from about 30 nanometers to about 200 nanometers. In addition, it has been found that NLPs can be used in a method for making carrier vehicle preparations which are mixed smaller and larger carrier vehicles, or having a larger mean size of about 200-300 nanometers, but improved encapsulation of passenger molecules.